The invention relates to a wing and a method for reducing the induced drag that is increased as a result of at least one propeller slipstream flowing onto a wing.
With propeller-driven aircraft there is an aerodynamic interaction between the propeller slipstream and the flow around the wing. This is of great significance in particular if the propeller/s is/are situated in front of the wing, for example in turboprop aircraft, e.g. the A400M. During operation propellers not only produce a thrust-generating flow component that acts in longitudinal direction of the aircraft, but also a flow component in circumferential direction of the propeller. This results in a propeller air flow (hereinafter also referred to as a “propeller slipstream”) that impinges in a helical or spiral shape on the wing surface that is situated behind it. Depending on the direction of rotation of the respective propeller this results in an increase or reduction in the local angle of attack on the wing. Consequently the lift distribution of the wing shows local increases or reductions in lift. As a result of such unevenness in the lift distribution the induced drag of the wing is increased.
From prior art, modifications of the wing leading edge are known which reduce disturbance caused by a propeller slipstream. The modifications have primarily been designed in order to delay airflow separation. However, in the case of non-separated airflow the influence on the wing lift distribution is small. Consequently the reduction in the induced drag is also relatively small.